package com.lagou.rpc.provider.hanlder;

import com.alibaba.fastjson.JSON;
import com.lagou.rpc.common.RpcRequest;
import com.lagou.rpc.common.RpcResponse;
import com.lagou.rpc.provider.anno.RpcService;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.SimpleChannelInboundHandler;
import org.springframework.beans.BeansException;
import org.springframework.cglib.reflect.FastClass;
import org.springframework.cglib.reflect.FastMethod;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.stereotype.Component;

import java.lang.reflect.InvocationTargetException;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;

/**
 * @ClassName: RpcServerHandler
 * @Description: 服务端处理类
 * 服务端业务处理类
 * 1.将标有@RpcService注解的bean缓存
 * 2.接收客户端请求
 * 3.根据传递过来的beanName从缓存中查找到对应的bean
 * 4.解析请求中的方法名称. 参数类型 参数信息
 * 5.反射调用bean的方法
 * 6.给客户端进行响应
 * @Author: qjc
 * @Date: 2021/9/20 22:33
 */
@Component
@ChannelHandler.Sharable  // 设置通道共享
public class RpcServerHandler extends SimpleChannelInboundHandler<String> implements ApplicationContextAware {
    /**
     * 通道读取就绪事件
     */
    @Override
    protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
        // 1. 接口客户端请求-将msg转化为RpcRequest对象
        RpcRequest rpcRequest = JSON.parseObject(msg, RpcRequest.class);
        RpcResponse rpcResponse = new RpcResponse();
        rpcResponse.setRequestId(rpcRequest.getRequestId());
        try {
            rpcResponse.setResult(handler(rpcRequest));
        } catch (Exception e) {
            e.printStackTrace();
            rpcResponse.setError(e.getMessage());
        }
        // 6. 给客户端进行响应
        ctx.writeAndFlush(JSON.toJSONString(rpcResponse));
    }

    /**
     * 业务处理逻辑
     *
     * @param rpcRequest
     * @return
     */
    private Object handler(RpcRequest rpcRequest) throws InvocationTargetException {
        // 3. 根据传过来的BeanName从缓存中查找对应的bean
        Object serviceBean = SERVICE_INSTANCE_MAP.get(rpcRequest.getClassName());
        if (serviceBean == null) {
            throw new RuntimeException("根据beanName找不到服务,beanName:" + rpcRequest.getClassName());
        }
        // 4. 解析请求中的方法名称，参数类型，参数信息
        Class<?> serviceBeanClass = serviceBean.getClass();
        Class<?>[] parameterTypes = rpcRequest.getParameterTypes();
        String methodName = rpcRequest.getMethodName();
        Object[] parameters = rpcRequest.getParameters();
        // 5. 反射调用Bena的方法-CGLIB反射调用
        FastClass fastClass = FastClass.create(serviceBeanClass);
        FastMethod method = fastClass.getMethod(methodName, parameterTypes);
        return method.invoke(serviceBean, parameters);
    }

    private static final Map SERVICE_INSTANCE_MAP = new ConcurrentHashMap();

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        Map<String, Object> serviceMap = applicationContext.getBeansWithAnnotation(RpcService.class);
        if (serviceMap != null && serviceMap.size() > 0) {
            for (Map.Entry<String, Object> item : serviceMap.entrySet()) {
                Object serviceBean = item.getValue();
                if (serviceBean.getClass().getInterfaces().length == 0) {
                    throw new RuntimeException("服务必须实现接口");
                }
                // 默认取第一个接口座位缓存bean的名称
                String name = serviceBean.getClass().getInterfaces()[0].getName();
                SERVICE_INSTANCE_MAP.put(name, serviceBean);
            }
        }
    }
}
